Cardiac arrhythmia is a disorder of rate, rhythm, or conduction of electrical impulses within the heart. They are often associated with coronary artery diseases, e.g. myocardial infarction and atherosclerotic heart disease. Arrhythmia can eventually cause a decrease of mechanical efficiency of the heart, reducing cardiac output. As a result, arrhythmia can have life-threatening effects that require immediate intervention. Many antiarrhythmic drugs act by blocking myocardial Na.sup.+ or Ca.sup.++ ion channels or by prolonging the cardiac action potential duration through the inhibition of potassium currents which are responsible for action potential repolarization.
Lu et al. isolated dicentrine and other alkaloids from the plant Lindera oldhamii (megaphylla) Hemsl (Yakugaku Zasshi, 92; 910-917, 1972), but they did not show any biological activity of these compounds.